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Which EFIE Do I Need?

Before we get into the details, please keep in mind that we recommend the Digital EFIEs for about 90% of all vehicles. We recommend these units for virtually all American cars, all foreign cars older than 1997, and most foreign cars after 1997. In the rest of the article we will cover why, and also the exceptions to the rule.

Quad Digital EFIE

Dual Digital EFIE

Basic Types of Oxygen Sensor

There are 2 basic kinds of oxygen sensor. They are called "narrow band" and the more modern, and superior, "wide band" oxygen sensor. These are discussed in more detail in Oxygen Sensors, Types of and Wide Band Oxygen Sensors. The most important distinction is which of these 2 types of oxygen sensors you have. An EFIE made for one type will not work on the other. If you have any doubt about this point, you can contact us and let us look up your vehicle to be sure.

It is often easy to figure out what type of sensors you have. Is your car pre 1997? Then it's narrow band. Is it an American Car? It's narrow band (we've now seen a few wide bands in 2009 American cars, but none before that). If it is a German or Japanese make and was built after 2000, then you should suspect that it has wide band sensors. Actually a very few cars started using wide band sensors in 1997, but it is only after 2000 that they are used with any regularity. But here's another test: Does the sensor have more than 4 wires? If it does, then its a wide band sensor. Note that Toyota and Honda uses a 4-wire wide band oxygen sensor. All other makes use 5-wire or 6-wire wide band sensors.

Here's another way to tell: Open your hood. Now look up. Do you see a sticker up under the hood with technical data about your vehicle? Often if you have wide band sensors, they are noted on these stickers for the mechanics. Note that it may be called an AFR (Air/Fuel Ratio) sensor, or AFS (Air/Fuel Sensor). These are all synonyms for a wide band oxygen sensor.

One other point: If you have wide band sensors upstream of the catalytic converter, you will still have narrow band sensors downstream. As of this date (2009), we have never seen wide band oxygen sensors being used downstream.

Number of Sensors

The next point is, "how many sensors do you have?". V-6, V-8 and larger, usually have 2 sensors that are upstream of the catalytic converter, one on each exhaust manifold. Further, they will have 1 or 2 downstream sensors as well. Note: some pre-1996 vehicles don't have downstream sensors. Vehicles with 4 cylinder engines usually have 1 upstream sensor, and 1 downstream sensor. You will occasionally run into some oddball configurations that vary from these, but these are the usual configurations.

We recommend that you treat all oxygen sensors regardless of whether they are upstream or downstream. Many manufacturers are now using the downstream sensors in their air/fuel calculations, and others are using them to check the function of the upstream sensors, causing odd trouble lights and poor mileage gains. Because this has become so prevalent, we designed our products to include EFIEs for both the upstream and downstream oxygen sensors. Please see our Digital EFIE Series and our Wide Band EFIE Series. These products include the correct combination of EFIEs to treat both your upstream and downstream sensors.

For instance, the Quad Digital EFIE has 2 digital EFIEs for treating 2 upstream narrow band oxygen sensors, and 2 analog EFIEs for treating 2 downstream sensors. Using analog EFIEs on the downstream sensors was not a cost saving consideration. We have found that analog EFIEs work better on downstream sensors, while digital EFIEs are clearly superior working on upstream sensors. For more information on why this is so, please see The New Digital EFIE: How It Works.

For those who have wide band sensors, we have created a similar product, the Wideband Quad EFIE, where we package 2 Wideband EFIEs combined with 2 Analog EFIEs for the 2 downstream sensors. Both the Wideband Quad EFIE and the Quad Digital EFIE, come in a version designed for 4 cylinder engines too. These have 1 EFIE (either Wideband or Digital) for a single upstream sensor and a single analog EFIE for a single downstream sensor.

Have Questions? Contact Us

We know it can be a little confusing at times, trying to figure out what device is best for your vehicle. If you would like help with this, you can Contact Us with the information on your vehicle and we will see that you get the product you need. We also have an online Sensor Request Form you can fill out, and we will email you back with the number and type of sensors you have and a recommendation for the EFIE product you'll need. Sometimes its just not clear which EFIE you need from the information you have available. In such cases, let us help you.